TPO and autoimmune thyroid disease: Despite the fact that the role of thyroid autoimmunity on natural conception and ART success rate remains debated, the current study allows to assume that antithyroid autoantibody positivity in euthyroid women with infertility, i.e., anti-thyroid peroxidase antibody, reflects a generalized immune response, as it exerts an effect on various steps of human reproduction starting from the ovarian tissue, composition of follicular fluid as a microenvironment for oocyte maturation, folliculogenesis and embryogenesis.